Economics of biological invasion: hound's tongue (Cynoglossum officinale) and livestock production in British Columbia

The exotic plant known as hound’s tongue (Cynoglossum officinale) invades rangelands in British Columbia (BC) and creates economic welfare losses to ranchers and the broader society through declining rangeland productivity, recreation opportunities, and soil fertility. In addition to such adverse effects, hound's tongue also disperses "burrs" that infest cattle and reduce their market value. I assume that a representative rancher attempts to maximize the profits from livestock sales subject to the growth of hound’s tongue in nearby rangelands. I develop a bio-economic model to demonstrate this management problem and derive the optimal allocation of labour for pulling hound’s tongue and the area of infested land at the steady state. My research findings show that the private steady state equilibrium is not considerably different from the social steady state equilibrium. Furthermore, a private rancher may be willing to control hound’s tongue in the neighbouring rangelands, once the marginal benefits from controlling hound’s tongue in his or her own rangeland becomes less than the marginal benefits of controlling hound’s tongue in the neighbouring public rangeland. Under such circumstances, government intervention to control hound’s tongue may yield few incremental social benefits. The findings of this study may have implications for the design of invasive plant management strategies. Instead of direct government intervention, offering incentives to private ranchers may be appropriate for controlling invaders such as hound’s tongue in rangelands in BC or elsewhere. If the intent of invasive plant management strategy is to provide support to ranchers more generally, then this may be better achieved via other means.